Chinese telecoms giants Huawei and ZTE have denied U.S. charges that they have connections with the Chinese government, amid allegations that their equipment and technology has 'backdoors' that could be used for foreign espionage.

The U.S. House Permanent Select Committee on Intelligence held an open hearing on "the national security threats posed by Chinese telecom companies doing business in the United States," which detailed a string of allegations pointed at the two of the largest telecoms equipment makers in the world.

The two firms, particularly Huawei, have found it difficult to make progress in the U.S. market due to the fears networks could be compromised by the Chinese government and its allies.

Huawei's senior vice-president Charles Ding strongly defended his company's case in front of the U.S. lawmakers:

"Huawei has not and will not jeopardise our global commercial success nor the integrity of our customers' networks for any third party, government or otherwise," according to the BBC.

"We will never do anything that undermines that trust. It would be immensely foolish for Huawei to risk involvement in national security or economic espionage," reiterating much the same sentiments by John Suffolk, former U.K. government chief information officer and currently Huawei's global security officer, in a report which stated that the firm would "never... tolerate such activities" such as hacking or espionage.

ZTE senior vice-president for North America and Europe Zhu Jinyun also testified at the hearing. He said that what people had been calling "back doors" are "actually software bugs" and that there was nothing sinister about the way the technology works.

He warned that ZTE should not be a focus of this investigation "to the exclusion of the much larger Western vendors."

The committee is close to completing a year-long investigation into the two firms, but there is little hope of a shining light at the end of the tunnel. The two sides are at loggerheads and there appears to be no resolution in sight, short of a monumental back-track by either side.

"We have heard reports about back doors or unexplained beaconing [a network self-repair technology] from the equipment sold by both companies," said Congressman Mike Rogers (R-MI), the committee's chairman.

According to sister-site CNET, members of the U.S. House were left "frustrated" and "unconvinced" by the testimony.

Both Huawei and ZTE will supply a list of their company's committee members who are also members of China's ruling Communist Party, something the U.S. House committee said they had previously declined to submit.